I had never heard or heard of "Liebe macht dumm" until coming across it in
Die schönsten Liebeslieder
in the early 1980's. Its melody is an old 18th century folk tune and the lyrics are by a certain Christian August Tiedje.
The song is a very amusing story of a hopeful suitor who, due to acute embarrassment is unable to express words of love to his intended whilst at a Sunday dance. It takes our hero some five verses before he can splutter out the stupid question of whether the day was Sunday or not. This of course, gets him precisely nowhere. Our unnamed hero finally in the last verse is obliged to admit that, "Liebe macht dumm" which translates as "Love makes you stupid"!